Children and adults with genetic eye diseases may be eligible for this study. Candidates will be screened with a medical and family history, thorough eye examination and blood test. The eye examination includes measurements of eye pressure and visual acuity (ability to see the vision chart) and dilation of the pupils with eye drops to examine the lens and retina (back part of the eye). Patients may also undergo additional diagnostic tests needed to determine eligibility for other NEI studies, including routine laboratory testing, imaging, questionnaires, a physical examination, and other standard and specialized tests and procedures as needed. In addition, patients will have special photographs taken of the eye to document the clarity or opacity of the eye lens. They will also undergo a procedure called electroretinography to assess the eye's response to bright lights. For this procedure, the eye is numbed with anesthetic drops and a contact lens is placed in the eye. The patient looks inside a large, hollow sphere and sees flashes of light, first in darkness and then in light. The contact lenses sense small electrical signals generated by the retina.